Snap door vent with spring

ABSTRACT

A vehicle ventilation opening is covered by a dome-shaped cover that has a pair of generally triangular oppositely disposed lateral cover openings extending from an uppermost portion of the cover. A pair of generally triangular shaped and outwardly bowed resilient doors are pivoted at opposite sides of the cover so that their adjacent but mutually spaced free end portions move between an inwardly displaced open position and a closed position wherein the free ends of the doors are at the high point of the domed cover and the doors seal against the inside of the cover at the peripheries of the openings. A compression spring is interposed between the adjacent free ends of the doors to force the doors against their hinged connections at the sides of the cover throughout all the positions of the doors and to facilitate an over-center toggle action which is provided by the resilient curved doors themselves to snap the doors to closed position and force them into sealing engagement with the peripheries of the cover openings.

The invention of this application is an improvement on the ventdisclosed and claimed in the co-pending application of Edmund D. Maciagfor Snap Door Vent, Ser. No. 957,449 filed Nov. 3, 1978 and assigned tothe assignee of the present application.

BACKGROUND OF THE INVENTION

Recreational vehicles such as campers, trailers, motor vans, motorcoaches and the like are commonly provided with ventilation devices toprovide for interior ventilation both during vehicle motion and when thevehicle is at rest. For ventilation during vehicle motion there iscommonly provided a streamlined body in the form of a scoop fixed to theexterior of the vehicle, to the side or to the roof, with a forwardlyfacing opening through which air is forced into the vehicle duringmotion. In some arrangements air is forced across the vehicleventilation opening and, by virtue of its flow across the opening,extracts air from the vehicle. One such arrangement is shown in U.S.Pat. No. 4,038,911 for multi-directional vent assigned to the assigneeof the present invention.

In almost all of such vehicle vents, as in most other types ofventilation devices, it is not only important that proper ventilation beprovided but it is essential that the opening be adequately sealed whenventilation is not desired. Thus, most prior devices have movable coversor doors and employ complex, expensive operators or latches that permitmovable vent doors to be shifted between closed and open positions, andwhich also firmly hold the parts in closed, sealed position. Forexample, U.S. Pat. No. 4,038,911 employs a widely used type of worm gearand bell crank linkage actuator. Although such an actuator effectivelymoves and holds the doors and covers in various positions, it is arelatively complex mechanism and is indirect in its operation since itrequires many turns of a handle and gearing to effect the desired doormotions.

Devices that employ a scoop to gather air flowing into a forwardlyfacing opening provide greatly increased wind resistance. Further, whena vehicle bearing such a vent enters a garage with a relatively lowdoorway, any contact of such a vent with fixed overhead structure islikely to result in irreparable damage to the vent.

Most vents of the prior art can take advantage of wind flow only in onedirection relative to the vehicle. Thus, when the vehicle is at rest,wind flowing from a direction other than the front of the vehicle willprovide relatively little ventilation of the interior. In theabove-mentioned patent a multi-vent directional vent is provided whichpermits effective ventilation with wind flowing in any direction butrequires two separate pivoted closure members and two separate gear andlinkage actuators for operating and sealing the closures.

Accordingly, it is an object of the present invention to provide a ventassembly that eliminates or minimizes above-mentioned problems.

SUMMARY OF THE INVENTION

In carrying out principles of the present invention in accordance with apreferred embodiment thereof a vent cover that is adapted to be securedto a vehicle in position to cover a ventilation opening thereof has afront wall that slopes rearwardly and outwardly to an outer cover regionthat is displaced outwardly from the ventilation opening. The coveropening is provided with a door positioned at least in part at the outercover region. The door has a pivotal connection to the cover and latchmeans exert a force on the door directed toward the pivotal connection.Preferably, the door and opening are of generally triangular shape.According to a feature of the invention the door is resilient and thelatch means are formed by a toggle that includes the resilient door andwhich holds the door in closed position. Sealing of the door in closedposition is still further enhanced by providing the door with an outwardcurvature and is still further enhanced by the generally triangularconfiguration of door and opening so that a compressive force exertedagainst the apex or short side of the triangular configuration door willtend to further curve the door outwardly and enhance the sealingpressure around the entire door periphery.

Conveniently, two laterally opposed openings and resilient doors areprovided with a compression member interposed to complete theover-center toggle action.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial illustration of a vent assembly embodyingprinciples of the present invention showing the assembly mounted uponthe roof of a vehicle.

FIG. 2 is a pictorial illustration, with parts broken away, lookingupwardly at the inside of the vent assembly, with the vehicle roof beingomitted.

FIG. 3 is a section taken on lines 3--3 of FIG. 1.

FIG. 4 is an enlarged fragmentary perspective of the interconnectionbetween free end portions of the two opposed doors.

FIG. 5 is an enlarged sectional detail showing the pivotal connection ofa door to the vent cover and frame, illustrating part of a peripheralseal.

FIG. 6 is a view similar to that of FIG. 3 but showing the doors in openposition.

FIG. 7 is a section taken on lines 7--7 of FIG. 6.

FIG. 8 is a sectional view of parts of a modified form of vent assembly,showing a compression linkage connected between the free ends of theresilient doors.

FIG. 9 illustrates still another modification of a toggle mechanism fordoor operation.

DETAILED DESCRIPTION

As illustrated in FIG. 1 a vent assembly is provided for mounting in anopening of a mobile or fixed shelter or camper type vehicle or the like.The vehicle conventionally has a structural wall member or roof 10 inwhich is cut an opening adapted to receive the vent assembly 12.Although the size and shape of the opening and mating vent assembly canbe varied according to particular requirements or design choice, it ismost common to make devices of this type of a rectangular or a squareconfiguration and such an arrangement is illustrated in the drawings.The vent assembly of the present invention would readily lend itself toa generally circular, eliptical or other curved configuration.Nevertheless, rectangular openings are more readily formed in a vehiclewall or roof and thus the illustrated configuration is presentlypreferred. The vent frame assembly includes a square vent frame having aperipheral wall 14 and a peripheral securing and sealing flange 16 thatcooperates with a frame ring 18 by means of which the vent assembly issecured to the structural wall member 10. Ring 18 is detachably securedto the frame flange 16 so that, upon mounting of the vent assembly, thestructural wall member 10 may be firmly clamped between the flange 16and ring 18 with suitable sealing means (not shown) interposed.Fastening means such as screws, nails, rivets, or the like (not shown)extend through the members 16, 18 to fixedly attach the vent assembly inconventional fashion to the structural wall member of the vehicle.

Integrally formed with the perimetric vent frame 14, 16 is a vent covergenerally indicated at 20. The vent cover has a dome-like configuration,extending outwardly of the vehicle wall ventilation opening andrearwardly from a forward portion 24 of the vent frame. The dome-likecover also extends forwardly from a rear portion 26 of the vent frameand laterally from both sides toward the dome center. Thus, the ventcover has an outwardly and rearwardly sloping front face 28 an outwardlyand forwardly sloping rear face 30, and laterally and outwardly slopingsides that all meet at an outer vent cover region 32 which is positionedat the outermost part of the dome-like vent cover.

The forward frame portion 24 is positioned toward the front of thevehicle to which the vent assembly is mounted and the rear frame portion26 is positioned toward the rear of the vehicle.

Forward face 28 of the cover includes relatively depressed side sections34, 36 each of generally triangular or gore shape, each slopingoutwardly and rearwardly from the front frame portion to the outer coverregion and each tapering from a wider front portion to a more narrowrear portion at the outer cover region. Similarly, rear face 30 hasdepressed side sections 38, 40 of generally triangular or gore shape,sloping outwardly and forwardly from wider portions at the rear of thevent assembly to more narrow portions adjacent the outer cover region32. Thus, the center of the vent cover has a longitudinally extendingcontinuous rib or raised reinforcing section formed by central sectionsof the front and rear faces 28, 30 and the outer region 32.

The cover is outwardly curved from side to side in a plane normal to thefore and aft direction and similarly curved from front to back in alongitudinally extending plane. The lateral section of the cover betweenfront and rear gores 34, 38 and side portion 42 of the cover, andopposite lateral cover section between gores 36 and 40 and cover sideportion 44, at the other side of the cover, each has a generallytriangular opening 50, 52 formed therein. The openings have relativelylong lateral edges 54, 56 respectively and relatively short interioredges, such as edges 58, which in effect, form the apices of thetriangular openings 50, 52.

The cover and frame are formed as an integral unit, as by injectionmolding or vacuum forming, for example, of a suitable strong andresilient plastic of the type commonly used for such ventilation covers.Such plastics include tenite, butyrate, polypropylene and ABS. The coverextends outwardly from the plane of the vehicle roof or wall opening fora total distance of approximately four inches or less in a presentlypreferred configuration. It presents a relatively low profile, curved inall directions, and is sufficiently strong and resilient so that it maybe readily deflected a reasonable amount upon impact with a fixedoverhead structure without any permanent deformation or damage.

Thus, it will be seen that the cover is of simple dome shape, having araised longitudinally extending reinforcing portion 28, 30, 32 and apair of relatively large oppositely disposed triangular lateral coveropenings.

A longitudinally extending hinge member is provided on each side of thecover in the form of arcuate channels 60, 61. The channels extend forthe full length of the long lateral opening edges 54, 56, each receivinga long cylindrical hinge bead 62, 63 formed upon and extending along thefull length of lateral edges of each of a pair of cover doors 64, 66.Each cover door is of generally triangular shape, having a configurationthat mates with the similar shape of its respective opening and isslightly larger than the opening so that door edge portions may overlapthe inner sides of the peripheries of the cover openings. Each door,being of a generally triangular shape, has a relatively long hinged sideon which is formed the hinge bead 62, 63 and a relatively short freeinterior end that is positioned adjacent the outermost cover region whenthe door is in closed position.

Each door is outwardly bowed, being convexly curved outwardly in atransverse plane that is perpendicular to the plane of the vent frame.The doors are not curved longitudinally. Outwardly facing continuousperimetric channels 70, 72 are formed in the respective doors and eachcarries therein a continuous resilient sealing strip 74, 76, formed ofrubber or a suitable sponge material or the like. To enhance sealingpressure on the seals 74, 76, the cover is formed with inwardlyprojecting perimetric ribs 78, 80 extending continuously around therespective cover openings. These ribs project into and deform the softsealing strips when the doors are closed to enhance sealing asillustrated in FIGS. 3 and 5.

Each door is pivoted to the side of the cover about a longitudinal axisextending through the central axes of the arcuate channels 60, 61 andcylindrical door beads 62, 63. The channel openings are slightly smallerthan the diameters of the respective beads whereby the beads may besnapped into position within the channels as the channel edges areresilinetly spread apart. Thus the doors are hinged to the cover for alimited amount of pivotal motion. The channel openings are sufficientlywide to enable the desired amount of pivotal motion as will be describedhereinafter. Obviously, conventional hinges or other types of hingearrangements may be employed to provide required pivotal motion of thedoors.

At the free interior end of each door there is formed a latch receivingmechanism in the form of cylindrical sleeves 84, 86, each closed at itslaterally outer end and having laterally inwardly facing open endsmutually aligned and spaced a small distance from one another. Acompression member in the form of a compression spring 88 has itsopposite ends captured within and bearing upon the closed ends of thesleeves 84, 86. Stop support members 90, 92 extend longitudinally acrossthe sleeves 84, 86 and have depending flanges 94, 96 at both front andrear. The flanges are apertured to receive respective ones of twolongitudinally extending headed pins 98, 100. Stop support members 90,92 have a generally angulated cross section with one leg lying parallelto the vent frame and the other normal to the frame when the door is inclosed position. A rectangular stop plate or connecting member 102 has acontinuous outwardly extending peripheral flange 104, front and backportions of which have laterally elongated slots 108, 110 which receivethe respective pins 98, 100 to provide a lost motion or pivotable andslidable connection between the stop plate and each door.

Longitudinally extending stop support members 90, 92 are each formedwith a plurality of longitudinally spaced laterally extending ribs 112,114 such as those indicated at 112, and 114 which bear against the stopmember flanges 104 in open position, thereby helping to limit motion ofthe doors beyond the position illustrated in FIG. 6. Plate 102 togetherwith pins 98, 100 and slots 108,110 also limit the opening motion of thedoors.

To the rear of the sleeves 84, 86 and spring 88 stop plate 102 is formedwith an inwardly projecting boss 120 (FIGS. 3, 6), having a bore thatslidably receives an operating handle shaft 122. Shaft 122 carries onits innermost end an operating knob 124 and on its outermost end aspring stop in the form of an enlargement 126. A compression spring 128is mounted on the shaft 122 and has its opposite ends bearingrespectively on the stop plate 102 and the enlargement 126.

In closed position, shown in FIG. 3, the doors are bent slightly beyondtheir unstressed condition and the spring 88 is under compression sothat the doors are each urged in respective counterclockwise andclockwise directions around their hinge axes as viewed in this figure.However, further motion beyond the illustrated closed position isresisted by abutment of the doors against the inner surfaces of theperipheries of the cover openings. To open the doors handle knob 124 isgrasped and pulled inwardly of the ventilation opening (downwardly asshown in FIG. 3) whereby the spring 128 moves stop plate 102 downwardlyand thus the free ends of the two doors are moved downwardly in unisonthrough the over-center position to the open position of FIG. 6. As thedoors reach the open position of FIG. 6, ribs 112, 114 of the stopmember supports 90, 92 abut the upstanding perimetric flange 104 of thestop plate 102 and further motion of the doors beyond the open positionis prevented. Upon release of the knob 124, after moving the doors tothe open position, spring 128 expands to raise the operating handlewhich no longer projects into the interior of the vehicle to anysignificant extent. The doors are closed by pushing up on the plate 102of knob 104 until the over center position is passed whereupon the doorssnap shut.

If deemed necessary or desirable a screen 125 may be fixed to and extendacross the vent frame. The screen is provided with an opening 127 of asize sufficient to allow the stop plate 102 to pass therethrough duringmotion of the doors between open and closed position.

The doors are formed of a suitable strong resilient plastic materialwhich may be the same as the material of which the cover is formed. In apresently preferred configuration the doors have little or no curvaturein a fore and aft direction of the vent whereas they are curved in thetransverse direction. Such transverse curvature enables the doors tomate with the like transverse curvature of the cover itself and, moreimportnatly, provides an improved closing and sealing action as will bedescribed below.

The described vent is symmetrical both about a fore and aft or alongitudinal axis extending from front frame portion 24 toward rearframe portion 26 and also about a transverse axis. However, it must beoriented upon a vehicle so that either frame portion 24 or frame portion26 is forward. In other words it can be mounted in either of twopositions 180° apart. The vent will operate best with the longitudinalextent of the reinforced cover portion 28, 30, 32 extending fore and aftof a vehicle on which it is mounted. In this orientation the vent actsas an air foil, deflecting air flowing to and over the front face 28,34, 36 of the vent outwardly of the vent assembly thereby increasingflow velocity. Increased flow velocity provides decreased air pressure.Thus, at the outermost cover region, in the area of the central section32 and laterally thereof, the air flows across the cover openings atincreased velocity and decreased pressure. Accordingly, with the doorsopen, in the position of FIG. 6, air is extracted from the interior ofthe vehicle.

Significant features of the described vent are the simple manner inwhich it is opened and closed and the improved sealing and latching inclosed position. The total lengths of the compression link (formed byspring 88 in this embodiment) and the two doors (as measured from theirpivots to the abutting ends of spring 88) is greater than the distancebetween the two door pivot axes. This provides an over-center toggleaction. Each door is closed by such toggle like or over-center action inwhich a force is exerted on the free interior end of the door, generallydirected toward the door hinge. Such force tends to compress the doorlaterally between its free end and its hinged side. Since the door isresilient and outwardly bowed in its normal unstressed condition, suchcompressive force tends to increase the bowing of the door.

The compressive force exerted upon the free end of each door can beprovided by many different mechanisms and in general by a compressionlink interposed between the opposed free ends and pressing against suchends to react compressive force on one door against compressive force onthe other. In the preferred arrangement of FIGS. 1-7, such reactivecompressive forces are conveniently provided by the spring 88. Thespring is under compression in all positions of the door as it movesbetween its closed position of FIG. 3 and its open position FIG. 6. Inthe closed position of FIG. 3 the spring exerts a force that is directedlaterally outwardly against each door and which has a component F_(L)that is exerted along a line 130 extending from the center of the closedend of sleeve 84 to the hinge axis, substantially in the plane of thecover opening. This component of the force tends to increase the normalunstressed outwardly convex curvature of the door. The spring force isexerted axially of the spring and thus parallel to the plane of the ventframe in closed position of the vent. The line of action of the springforce (the spring axis) is displaced outwardly of the door hinge axesand thus exerts a closing moment of force.

Particularly because of the triangular shape of the door the compressiveforce exerted at the apex of the door triangle (actually at its freeend) subjects the front and back door edges themselves to compressiveforce which tends to increase the bending of such front and back edges.It is at these edges that a significant part of the door sealing isaccomplished. The triangular door configuration thus translates theforce exerted laterally by the spring on the door free ends into sealingforce F_(O) that press the lengths of the door front and back edgesoutwardly against the overlapped periphery of the covering opening.

The equal and opposite reactive edge forces exerted by the compressionspring 88, are directed generally toward the door hinges at the lateraledges of the doors but actually extend at a small angle to the plane ofthe cover openings, an angle in the order of 20° for example, and eachthereby produces a moment of force that tends to close the door andmaintain it in its closed position. Thus, sealing of the doors at theirfree ends is also enhanced and the doors are firmly held in closedposition by forces represented at F_(I).

It will be seen that the described arrangement of the two opposed doorswith an interposed compression member 88 provides an over center ortoggle type action. As the doors move from the closed position of FIG. 3toward the open position of FIG. 6 their adjacent free ends move insimilar arcuate paths that approach each other at an intermediateposition. Thus the distance between the free ends decreases. Thisdecrease in distance is accommodated, in the arrangement of FIGS. 1-7,by resilient deformation of the doors and also by compression of thespring 88. The strength of spring 88 is made sufficiently great so thatits resistance to axial compression is greater than compressive bendingresistance of the outwardly bowed doors. Stated otherwise, thecompliance of the spring is less than the compliance of the resilientdoors so that the dimensional change of the doors (by increased bowing)is greater than the decrease of spring length during over-center action.In a preferred mechanization, about three fourths of the deformationrequired for the over-center action is accounted for by increasedbending of the resilient doors. In fact, in some embodiments (to bedescribed below) the interposed compressive member (analagous tocompression spring 88) is a solid metal or plastic link or bar and mayexperience negligible compressive deformation. Therefore, the doorsthemselves provide most of the toggle or over the center action thattakes place in motion of the doors between open and closed position. Theparts are dimensioned and resiliencies of the several components chosenso that with the doors in the closed position of FIG. 3 a significantcompressive force is still exerted by the spring against the free endsof the door and thus each is slightly bowed further upwardly, from itsnormal unstressed configuration, under the influence of this force. Thisfurther outward bowing in closed position results in increasedcompression and further deformation of the resilient sealing strips 74,76.

Since many plastic materials exhibit a tendency to creep or change shapeand dimension under stress, the curvature of the plastic resilient doorsmay increase with time, or the doors may warp or otherwise change shape.The compressive spring 88 not only accommodates such changes but alsoenables less stringent dimensional tolerances in manufacture.

As mentioned above, elasticity of the doors themselves is significantlyinvolved in the over-center toggle action. In fact, the interposedcompression member 88 may have a greater amount of resistance todeformation and, in a limiting case, may be comprises of a solid bar orlink extending between and abutting against the facing free ends of thetwo doors. Thus, as shown in FIG. 8 a door operating and latching togglelinkage may comprise a threaded screw 140 having an end rotatablycaptured in a fitting 142 that is secured to and extends inwardly of theouter cover region. The screw is received in a threaded nut 144 that ispivotally connected to rigid links 146, 148 which in turn are pivoted tofree ends of the two doors 150, 152. The cover, doors and theirinterconnections are identical to those previously described except forthe toggle linkage.

In the arrangement of FIG. 8 substantially all of the deflectionrequired for the over-center toggle action takes place by increasedbending of the doors. The described toggle links 144, 146 and 148continue to reactively exert compressive edge forces on the door ends tomaintain the doors in closed position and to enhance sealing against thecover openings. The doors are opened and closed by rotating screw 140.

As the screw rotates in one direction the doors are moved in unison tothe open position. Rotation of the screw in the other direction movesthe doors in unison to the illustrated closed position. Further motionof nut 144 may be limited by abutment of the links with inner sections154, 156 of the nut. Thus link 146 can pivot clockwise but not counterclockwise relative to nut 144 from the illustrated position. Similarlylink 148 can pivot counter clockwise but not clockwise (as viewed inFIG. 8).

Still another modification of a door opening mechanism is illustrated inFIG. 9 wherein doors 160, 162 are identical to doors 64, 66 previouslydescribed except for the toggle linkage interconnecting the adjacentfree end portions of the doors. In this arrangement a bell crank lever164 is pivoted at ends 166, 168 of a first lever arm 169 to therespective adjacent free ends of the two doors. The second arm 170 ofthe bell crank lever is pivoted at 172 to a curved end of an operatingrod 174. To move the door from the open position illustrated in solidlines, to the closed position, illustrated in dotted lines in FIG. 9,rod 174 is pulled downwardly and then pivoted outwardly (counterclockwise as viewed in FIG. 9) to be secured by means such as a Velcrofastening strip 176 to a portion of the screen 178 extending across thevehicle ventilation opening. The door pivots are both shifted slightlyinwardly to accommodate the pivotal motion required by the bell crank.

In the arrangement of FIG. 9 arm 169 of the bell crank lever betweenpivot points 166, 168 is under compression in the closed position of thedoors and thus exerts oppositely directed reactive forces against thedoor edges tending to increase the outward curvature thereof, to enhancethe sealing and to maintain the doors in closed position.

Although a presently preferred mechanization of the invention embodies apair of lateral opposed doors mounted in a vent cover having bothlongitudinal and transverse symmetry, it will be readily understood thatprinciples of the invention may be applied to vent covers without suchsymmetry and which include one door or three or more doors. For a coverthat has but one opening and one door the compression member, such asthe spring 88 or an equivalent relatively rigid compression link, hasone end mounted for motion together with its opposite end (the endbearing upon the door edge) so as to maintain the compressive forcedirected against the door edge and generally in the plane of the doorthroughout at least a portion of the door motion from the closedposition. Such a single door and its opening could be located either onone side or to the rear of the outer cover region.

For three or four doors a compression member interposed between theadjacent free ends of all of the doors comprises a single hub havingseveral compressive arms or compression springs extending to the freeends of each of the several doors, respectively, so that all doors arecompressively bowed against the same centrally located compressionmember and all doors move in unison between open and closed positions.

In the embodiments of FIGS. 1-7 and 9, the doors will spring open if thevent strikes a low overhanging object and little or no permanent damagemay be suffered.

The foregoing detailed description is to be clearly understood as givenby way of illustration and example only, the spirit and scope of thisinvention being limited solely by the appended claims.

We claim:
 1. A vehicle vent assembly comprisinga vent frame adapted tobe mounted in an opening of a vehicle and having front, back and sideportions, a vent cover fixed to said frame and having a cover bodyextending rearwardly and outwardly from a front portion of said ventframe to provide an area of decreased pressure as said vehicle movesforwardly, said cover body having a cover opening extending across atleast a part of said area of decreased pressure laterally toward a sideportion of said vent frame, a resilient door, means for mounting saiddoor for motion to a first position wherein said cover opening is closedand sealed by said door and to a second position wherein said door isdisplaced inwardly from said cover opening at said area of decreasedpressure, and toggle means including a compression spring abutting anedge portion of said door for holding said door in said second position,wherein said spring tends to compress and said door tends to bend as thedoor moves between said portions, and wherein compliance of said door isgreater than compliance of said spring whereby said door will experiencea greater dimensional change than the spring during motion between saidpositions.
 2. A vent assembly for a vehicle having a ventilation openingformed in a wall thereof, said assembly comprisinga vent cover adaptedto be fixed to a vehicle wall to cover a ventilation opening therein,said vent cover comprising a front wall portion sloping rearwardly andoutwardly to an outer vent region, whereby air flowing over said ventassembly is deflected by said front wall portion to flow with decreasedpressure at said outer vent region, said vent cover having a pair ofopposed cover openings extending laterally in opposite directions acrossat least part of said outer vent region, first and second doors havingremote sides pivotally connected to said cover and having adjacentmutually spaced free end portions, said doors being movable to a firstposition wherein said cover openings are closed and sealed by said doorsand to a second position wherein said doors are displaced inwardly ofsaid cover openings at said outer vent region, and a compression springinterposed between said free end portions, wherein each free end portioncarries an outwardly opening sleeve, said spring having opposite endsthereof received in said sleeves.
 3. The vent assembly of claim 2including a means for interconnecting said doors to limit relativemotion thereof.
 4. The vent assembly of claim 3 wherein said means forinterconnecting comprises a connecting member having a movableconnection with both said doors, whereby said doors may be moved inunison between said positions by moving said connecting member relativeto said vent cover.
 5. A vehicle vent assembly comprisinga vent frameadapted to be mounted in an opening of a vehicle, said vent frame havingfront, back and side members, a vent cover fixed to said frame andhaving a generally dome-like configuration sloping rearwardly andoutwardly to an outer dome region and sloping forwardly and outwardly tosaid outer dome region, said vent cover having a pair of mutuallyopposed cover openings therein each sloping outwardly from a respectiveone of said side members toward said outer dome region, each saidopening having a relatively small extent adjacent said outer dome regionand having a relatively great extent on the side thereof remote fromsaid outer dome region, first and second doors pivoted to said cover andside members adjacent said side members and each having a free end, eachsaid door having a shape substantially conforming to the shape of arespective one of said openings and being slightly larger than theassociated opening to overlap opening perimeters, said doors beingpivotally movable to a closed position in overlapping engagement withthe perimeters of said openings and to an open position in which saidfree ends are displaced inwardly of said cover, and compression springmeans interposed between said free ends for holding said doors in saidclosed position, wherein the doors and spring are dimensioned to providean over-center toggle action, and wherein at least one door is outwardlybowed and has a compliance less than the compliance of said spring.